systemc: Purposefully *expose* bind in the initiator socket.

Apparently the base version of bind actually *is* supposed to be
accessible, so expose it with using instead of hiding it.

Change-Id: Ie762c35d6322e744696ed597189b7773ea68c3b7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23322
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/systemc/ext/tlm_core/2/sockets/initiator_socket.hh

@@ -120,6 +120,8 @@ class tlm_base_initiator_socket :
         (s.get_base_export())(get_base_export());
     }
 
+    using port_type::bind;
+
     void operator() (base_type &s) { bind(s); }
 
     //
@@ -169,9 +171,6 @@ class tlm_base_initiator_socket :
 
   protected:
     export_type m_export;
-
-  private:
-    using port_type::bind;
 };
 
 //